Island Of The Colorblind Summary

Island of the Colorblind is written by neurologist Oliver Sacks in which he demonstrates his passion for islands and reveals his experience during an expedition to an isolate colorblind community on the Micronesian islands of Pingelap and Pohnpei. Sacks is so intrigued about an islands ability to cause isolation, extinction and new forms of life that he considered Pingelap an ideal location to explore a civilization where colorblindness known as achromatopsia, is the standard. He views these islands as experiments of nature, where life can take a separate evolutionary path due to its’ isolated environment. (pg 4) To understand what the visual world would be like for those who were born completely colorblind, he decided to embark on a voyage …show more content…
In the late 18thcentury, Pinelap was struck by a devastating typhoon killing 90% the population. (pg 36) Leaving approximately 20 survivors. Inbreeding was necessary in order to restore the population, and by the 4th generation Achromatopsia appeared. Pg 37. This rare disease all of a sudden had increased to about 5% of the population, and about 30% of the population are carries (1ST on M). This caused a problem, because today’s affected inhabitants are all able to trace their ancestry to the same survivor, Nanmwarki Mwahuele. He is believed to be the only carrier in his generation (1st on M- Morton) This demonstrates the islands ability enable two phenomenons known as the bottle neck effect and genetic drifft . The bottle neck effect occurs when a population suddenly reduces in size. While the genetic drift is defined by the change in frequency of an allele. The alleles in the offspring are sample of those in …show more content…
Those myths range from the sun blinding a fetus while in the womb, to thinking that the disease could have been brought from the outside world by contamination or a result of a curse. (pg 53). Achromatopsia is not a curse or a form of punishment due to sinning. It is an unpreventable, incurable hereditary disorder. The cause of this complete colorblindness lies in the genetics. According to Hum (1972) achromatopsia is a autosomal recessive trait which constitutes total lack of color vision, poor visual acuity, and excessive squinting. (sieving) This is a disorder in which symptoms appear after the first 2 months of life. Also, they determined that it is nonprogressive and does not influence survival. (HUM 1972) . Achromatopsia is caused by a mutation in three genes: cyclic nucleotide gated channel beta 3 (CNGB3) gene, cyclic nucleotide gated channel alpha 3 (CNGA3), and GNAT2. (Sieveing) CNGB3 and CNGA3 genes code for the making of subunits in the cone photoreceptor cyclic nucleotide-gated (CNG) channel. (Sieving) These mutations impair cone function. (M3 Sieving). These channels are solely found in cones, also known as light detecting cells, whose role is to provide vision in bright light, such as color vision and fine resolution. (PANG) The impairment of cones results in achromatopsia. In contrast, the rods, which are contribute to vision in dim light are